It generally is recognized that the American diet is unbalanced in that it does not contain adequate amounts of necessary nutrients required to help maintain or improve health. Often, processed foods containing high calories, saturated fats, sodium and refined sugar are consumed in excess, while beneficial foods, such as fruits and vegetables, which are high in potassium, fiber, certain fats, vitamins, minerals, and antioxidants, are under-consumed. The United States Department of Agriculture estimates that less than 30% of all children and adults consume the recommended 5 to 7 servings of fruits and vegetables per day. Consequently, obesity and other health problems related to the diet are common.
Efforts to improve the American diet and eating habits towards healthier foods generally have failed. Societal drivers such as working couple families, lack of time for proper meal preparation, and lack of knowledge, contribute to resistance towards healthier eating habits. Additionally, consumers often are required to sacrifice taste, to switch from a familiar brand product, or to completely change their behavior to improve their nutritional intake. Further, the ubiquity of marketing for Quick Serve Restaurants and “junk” foods influences the general population's psyche and behavior.
A novel way to improve the American diet is through fortification of everyday foods and beverages, including quick serve restaurant preparations, with the complete nutrition of fruits and vegetables. This can be especially effective if the consumer is not required to sacrifice taste, change brand, or substantially change behavior in any way. The described invention provides methods and compositions for fortification of base foods with the complete nutrition of fruits and vegetables of common foods and beverages, including those from Quick Serve Restaurant preparations, to improve the American diet The described invention further provides methods for determining the complete nutritional value of a standard equivalent unit of fruits and vegetables for human consumption, and fortification products which contain all the individual nutritional components of nutrition equal to multiple standard equivalent units of fruits and vegetables.
I. Nutrition Basics Why Balanced Nutrition is Important
Foods are grouped together when they share similar nutritional properties. The food groups in an American diet generally include grains (including, but not limited to, whole wheat bread and rolls, whole wheat pasta, pita bread, cereals, oatmeal, brown rice); fruits (including, but not limited to, apples, apricots, bananas, dates, grapes, oranges, grapefruit, grapefruit juice, mangoes, melons, peaches, pineapples, raisins, strawberries, tangerines); vegetables (including, but not limited to, broccoli, carrots, collards, green beans, green peas, kale, lima beans, potatoes, spinach, squash, sweet potatoes, tomatoes); fat-free or low-fat milk and milk products (including, but not limited to, fat-free (skim) or low-fat (1%) milk or buttermilk, fat-free, low-fat or reduced-fat cheese, fat-free or low-fat regular or frozen yogurt); lean meats, poultry and fish (including, but not limited to, beef, poultry, pork, game meats, fish, shellfish); nuts, seeds, and legumes (including, but not limited to, almonds, hazelnuts, mixed nuts, peanuts, walnuts, sunflower seeds, peanut butter, kidney beans, lentils, split peas).
A healthy eating plan provides information regarding how much a person should consume from each food group to stay within the person's calorie needs and promote good health.
Health professionals recognize the benefits associated with a healthful eating plan based on the Dietary Guidelines for Americans, which has been published every 5 years since 1980 by the United States Department of Health and Human Services (HHS) and the Department of Agriculture (USDA). The Guidelines provide authoritative advice for people two years of age and older about how good dietary habits can promote health and reduce risk for major chronic diseases. They serve as the basis for Federal food and nutrition education programs.
Two examples of eating plans are identified by the Dietary Guidelines for Americans 2005: (1) the USDA Food Guide, offered through MyPyramid.gov and (2) DASH Eating plan (Dietary Approaches to Stop Hypertension). MyPyramid.gov was developed to help individuals create meal plans specific to their needs and takes into account a person's sex, age, height, weight, and physical activity level. The DASH eating plan was developed by researchers funded by the National Institutes of Health (NIH) to learn if certain nutrients in foods would help reduce blood pressure. Studies reported that this eating plan, particularly when combined with eating less sodium, lowered blood pressure. Although the plan was developed to help lower blood pressure, it may offer a healthy approach to eating that can benefit most adults. Both the USDA Food Guide and DASH Eating Plan are healthy eating plans that (1) focus on fruits, vegetables, whole grains, and low-fat or fat-free milk and milk products; (2) include lean meats, poultry, fish, beans, eggs, and nuts; (3) are low in saturated fats, trans fats, cholesterol, salt (sodium), and added sugars; and (4) can provide information regarding a person's daily calorie needs.
Food Components
Food is any substance, usually composed of carbohydrates, fats, proteins, vitamins and minerals, and water, that can be eaten or drunk by an animal, including humans, for nutrition or pleasure.
Water
Water (H2O) is a ubiquitous chemical substance that is essential for terrestrial life. Water assists in regulating body temperature, lubrication of joints, protection of organs, and in eliminating body wastes. Water can dissolve many different substances, imparting varying tastes and odors; pure water is tasteless and odorless. Healthy individuals meet their fluid needs by drinking when thirsty and drinking fluids with meals. Fluids also may be obtained through foods such as broth soups.
Dietary Fat
Fats are essential constituents of food for many animals, with a calorific value per weight twice that of carbohydrates. In many animals, excess carbohydrates and proteins are converted into fats for storage. Mammals store fats in specialized connective tissues (adipose tissues), which not only act as energy reserves but also insulate the body and cushion its organs.
Fat, in the broadest sense, is a mixture of lipids (meaning biological molecules soluble in apolar solvents, but only slightly soluble in water), mainly triglycerides (meaning lipids containing three fatty acid molecules linked to a molecule of glycerol). More specifically, the term “fat” refers to a lipid mixture that is solid at room temperature; lipid mixtures that are liquid at room temperature are referred to as “oils.” Fats are insoluble in water.
A “fatty acid” is chemically denoted as R—COOH, where R is a chain of carbon atoms. The common fatty acids of biologic origin are linear carbon chains with an even number of carbon atoms, e.g., n-tetradecanoate, or myristate, with 14 carbon atoms; n-hexadecanoate, or palmitate, with 16 carbon atoms; and n-octadecanoate, or stearate, with 18 carbon atoms. Fatty acids have four major physiologic roles. (1) They are building blocks of phospholipids and glycolipids, which are important components of biological membranes; (2) many proteins are modified by the covalent attachment of fatty acids, which targets them to membrane locations; (3) fatty acids are fuel molecules, which are stored as triacylglycerols (also called neutral fats or triglycerides), which are uncharged esters of glycerol; and (4) fatty acid derivatives serve as hormones and intracellular messengers. Essential fatty acids, or EFAs, are fatty acids that cannot be constructed within an organism from other components by any known chemical pathways, and therefore must be obtained from the diet.
A saturated fat is “saturated” with hydrogen atoms, i.e., every carbon atom in the carbon chain is attached to two hydrogen atoms except at the end of the chain, which bears three hydrogen atoms. There are several kinds of naturally occurring saturated fatty acids, which differ by the number of carbon atoms, ranging from 3 carbons (propionic acid) to 36 carbons (hexatricontanoic acid). Examples of foods containing a high proportion of saturated fat include dairy products (especially cream and cheese), animal fats such as suet, tallow, lard and fatty meat, coconut oil, cottonseed oil, palm kernel oil, and chocolate. Diets high in saturated fat have been correlated with an increased incidence of atherosclerosis and coronary heart disease.
An “unsaturated fat” is a fat or fatty acid in which there are one or more double bonds in the fatty acid chain. Where double bonds are formed, hydrogen atoms are eliminated. Since the carbon atoms in an unsaturated fat are double-bonded to each other, there are fewer bonds connected to hydrogen, resulting in fewer hydrogen atoms A fat molecule is “monounsaturated” if it contains one double bond, and “polyunsaturated” if it contains more than one double bond.
The terms “cis” and “trans” refer to the arrangement of the substituents of carbon atoms across a double bond. In the cis arrangement, the substituents are on the same side of the double bond The rigidity of the double bond freezes its conformation and, in the case of the cis isomer, causes the chain to bend and restricts the conformational freedom of the fatty acid. The more double bonds the chain has in the cis configuration, the less flexibility it has. In the trans arrangement, the substituents are bound to opposite sides of the double bond. As a result, they do not cause the chain to bend much, and their shape is similar to straight saturated fatty acids. In most naturally-occurring unsaturated fatty acids, each double bond has three n carbon atoms after it, for some n, and all are cis bonds.
A trans fatty acid or “trans fat” is an unsaturated fatty acid molecule that contains a trans double bond between carbon atoms. Trans fats may be monounsaturated or polyunsaturated, but are never saturated. Most fatty acids in the trans configuration (trans fats) are not found in nature and are the result of human processing (e.g., hydrogenation). The process of hydrogenation adds hydrogen atoms to cis-unsaturated fats, eliminating a double bond and resulting in a more saturated fat that has a higher melting point, which makes it attractive for baking and extends shelf-life. However, the process frequently has a side-effect of turning some cis-unsaturated fats into trans-unsaturated fats. Trans fats from partially hydrogenated oils are more harmful than naturally occurring oils.
Cholesterol is a waxy steroid that modulates the fluidity of eukaryotic membranes and is the precursor of steroid hormones, such as progesterone, testosterone, estradiol and cortisol. It is a component of all eukaryotic plasma membranes, and is essential for the growth and viability of cells in higher organisms. However, high serum levels of cholesterol cause disease and death by contributing to the formation of atherosclerotic plaques in arteries throughout the body. Low density lipoprotein (LDL), the major carrier of cholesterol in blood, transports cholesterol to peripheral tissues and regulates de novo cholesterol synthesis at these sites. High-density lipoprotein (HDL), picks up cholesterol released into the plasma from dying cells and from membranes undergoing turnover. It is believed that the consumption of trans fats increases the risk of coronary heart disease by raising levels of “bad” low-density lipoprotein (LDL) cholesterol and lowering levels of “good” high-density lipoprotein (HDL) cholesterol.
Major dietary sources of cholesterol include cheese, egg yolks, beef, pork, poultry and shrimp. Total fat intake, especially saturated fat and trans fat, plays a larger role in the level of cholesterol in blood than does the intake of cholesterol itself.
It generally is recommended that most of the intake of dietary fat should come from unsaturated sources (i.e., polyunsaturated fats and monosaturated fats). For example, nuts, vegetable oils, and fish are sources of unsaturated fats. However, some studies have reported that polyunsaturated oils, such as soya, canola, sunflower and corn, degrade easily to toxic compounds and trans fat when heated.
The Dietary Guidelines for Americans 2005 recommend a total fat intake within a certain limit. This limit is defined as a percentage of a person's total calorie needs. It recommends that children ages 2 to 3 have a total fat limit 30% to 35% of total calories; children and adolescents ages 4 to 18 have a total fat limit of 25% to 35% of total calories; and adults ages 19 and older have a total fat limit of 20% to 35% of total calories. Trans fats, saturated fats and cholesterol are less healthy than polyunsaturated and monounsaturated fats.
Few Americans consume less than 20% of calories from fat. Fat intake that exceeds 35% of calories are associated with increased saturated fat intake and increased calorie intake, To decrease the risk of elevated LDL cholesterol in the blood, most Americans need to decrease the intake of saturated fat and trans fat, and many need to decrease their dietary intake of cholesterol. It especially is important for men to meet this recommendation, since men tend to have higher intake of dietary cholesterol. Population-based studies of American diets show that intake of saturated fat is more excessive than intake of trans fats and cholesterol. Therefore, it is most important for Americans to decrease their intake of saturated fat. However, intake of all three should be decreased to meet recommendations.
Studies have reported that the estimated average daily intake of trans fats in the United States is about 2.6% of total energy intake. Processed foods and oils provide approximately 80% of trans fats in the diet, compared to 20% that occur naturally in food from animal sources. Trans fat content of certain processed foods has changed and is likely to continue to change as the food industry reformulates products. The food industry has an important role in decreasing trans fatty acid content of the food supply since trans fatty acids produced in the partial hydrogenation of vegetable oils account for more than 80% of total intake. Limited consumption of foods made with processed sources of trans fats provides the most effective means of reducing intake of trans fats.
Carbohydrates
A carbohydrate is an organic compound with general formula C.(H20), and related compounds with the same basic structure but modified functional groups. In food science, and in many informal contexts, the term “carbohydrate” often means any food that is particularly rich in starch (such as cereals, bread and pasta) or sugar (such as candy, jams, and desserts).
For dietary purposes, carbohydrates can be classified as simple (monosaccharides and disaccharides) or complex (oligosaccharides and polysaccharides). The term “complex carbohydrates” also may be used to denote fruit, vegetables, and whole grains. Carbohydrates are part of a healthy diet. Dietary guidelines generally recommend that complex carbohydrates, nutrient-rich simple carbohydrate sources (such as fruit), and dairy products make up the bulk of carbohydrate consumption. The Acceptable Macronutrient Distribution Range (AMDR) for carbohydrates is 45% to 65% of total calories. Carbohydrates supply energy to the body in the form of glucose, which is the only energy source for red blood cells and is the preferred energy source for the brain, central nervous system, placenta, and fetus. Sugars can be present naturally in foods (for example, the fructose in fruit or the lactose in milk) or added to the food. Added sugars, sometimes referred to as “caloric sweeteners,” are sugars and syrups added to foods at the table, during processing, or during preparation (e.g, high fructose corn syrup in sweetened beverages and baked products). Although the body's response to sugars does not depend on whether they naturally are present in a food or added to the food, added sugars supply calories but few or no nutrients. Consequently, it is important to choose carbohydrates wisely. Foods in the basic food groups that provide carbohydrates (for example, fruits, vegetables, grains and milk) are important sources of many nutrients. Consumption of added sugars provides calories while providing little, if any, of the essential nutrients. The greater the consumption of foods containing large amounts of added sugars, the more difficult it is to consume enough nutrients without gaining weight.
Dietary Fiber
Dietary fiber is composed of nondigestable carbohydrates. Diets rich in dietary fiber have a number of beneficial effects, including a decreased risk of coronary heart disease and improvement in laxation.
The recommended dietary fiber intake is 14 g per 1000 calories consumed. Some Americans find it challenging to achieve this level of intake. Increasing the proportion of fruit that is eaten in the form of whole fruit rather than juice is desirable to increase fiber intake as it generally is recommended that the majority of servings from the fruit group should come from whole fruit rather than juice. However, inclusion of some juice, such as, for example, orange juice, can help meet recommended levels of potassium intake.
Legumes, such as, for example, dry beans and peas, are especially rich in fiber and it is recommended they be consumed several times per week. Legumes are considered part of both the vegetable food group and the meat and beans food group as they contain nutrients found in each of these food groups.
It is important to consume at least half the recommended grain servings as whole grains for all ages, at each calorie level, to meet the fiber recommendation. Consuming at least three ounce-equivalents of whole grains per day may reduce the risk of coronary heart disease, may help with weight maintenance, and may lower risk for other chronic diseases.
Dietary fiber also is important for laxation. Since constipation may affect up to 20% of people over 65 years of age, older adults should choose to consume foods rich in dietary fiber.
Carbohydrate intake by children need special considerations with regard to obtaining sufficient amounts of fiber, to avoiding excessive amounts of calories from added sugars, and to preventing dental caries. Several cross-sectional surveys on U.S. children and adolescents have reported inadequate dietary fiber intake, which could be improved by increasing consumption of whole fruits, vegetables, and whole-grain products. Sugars may improve the palatability of foods and beverages that otherwise might not be consumed, however, beverages with caloric sweeteners, sugars and sweets, and other sweetened foods that provide little or no nutrients are associated negatively with diet quality and can contribute to excessive energy intake, affirming the importance of reducing added sugars intake substantially from current levels.
Sugars
The simplest carbohydrates are sugars (monosaccharides, such as, for example, glucose and fructose, and disaccharides, for example, sucrose), which are soluble compounds. Monosaccharides are the simplest carbohydrates in that they cannot be hydrolyzed to smaller carbohydrates.
Under current regulations, food labels contain a Nutrition Facts Panel, which provides the amount of total sugars in the product, but does not list added sugars separately. It is recommended that individuals examine the ingredient list to ascertain whether a food contains added sugars. Ingredients are listed in order of performance, by weight (i.e., the ingredient with the greatest contribution to the product weight is listed first and the ingredient contributing the least amount is listed last). Added sugars that may appear on food labels include, but are not limited to, brown sugar, corn sweetener, corn syrup, dextrose, fructose, fruit juice concentrates, glucose, high-fructose corn syrup, honey, invert sugar, lactose, maltose, malt syrup, molasses, raw sugar, sucrose, sugar and syrup.
Individuals who consume food or beverages high in added sugars tend to consume more calories than those who consume food or beverages low in added sugars; they also tend to consume lower amounts of micronutrients. Some studies have reported a positive association between the consumption of calorically sweetened beverages and weight gain. Accordingly, decreased intake of such foods, especially beverages with caloric sweeteners, is recommended to reduce calorie intake, to help achieve a recommended nutrient intake, and to achieve weight control.
Sugars and starches contribute to dental caries by providing a substrate for bacterial fermentation in the mouth. Thus, the frequency and duration of consumption of starches and sugars can be important factors for dental hygiene. To help reduce the risk of dental cares, fluoridated water and/or fluoride-containing dental hygiene products are recommended. Most prepackaged bottled water is not fluoridated. With the increase in consumption of bottled water, there is concern that Americans may not be getting enough fluoride for maintenance of oral health.
Protein
Proteins are large complex molecules or polypeptides composed of amino acids. Proteins are essential parts of organisms and participate in virtually every process within cells. Most microorganisms and plants can biosynthesize all standard 20 amino acids, the building blocks of proteins, An essential amino acid is an amino acid required by an organism but that cannot be synthesized de novo from other compounds, and therefore must be supplied in the diet, while the others are termed nonessential. These designations refer to the needs of an organism under a particular set of conditions. Using the basic set of 20 amino acids, the essential amino acids for humans are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine, and the nonessential amino acids are alanine, arginine, asparagine, aspartate, cysteine, glutamate, glutamine, glycine, proline, serine and tryosine.
In animals, amino acids are obtained by consumption of foods containing protein. Ingested proteins are broken down through digestion, which typically involves denaturation of the protein through exposure to acid and hydrolysis by proteases. Some ingested amino acids are used for protein biosynthesis, while others are converted to glucose through gluconeogenesis, or fed into the citric acid cycle, which completes the metabolic breakdown of glucose molecules to carbon dioxide. Proteins are found in, for example, meats, poultry, fish, legumes (dry beans and peas), tofu, eggs, nuts and seeds, milk and milk products, and grains. It generally is recommended that 10% to 35% of the daily caloric intake come from protein. Table 1 shows the recommended dietary allowances (RDA) for different age groups.
TABLE 1Recommended Dietary Allowance for ProteinRecommended Dietary Allowance for ProteinGrams of ProteinNeeded Each DayChildren ages 1-313Children ages 4-819Children ages 9-1334Girls ages 14-1846Boys ages 14-1852Women ages 19-70+46Men ages 19-70+56Tryptophan
For many organisms, the amino acid tryptophan (Trp, W) is an essential amino acid. Tryptophan functions as a biochemical precursor for several compounds including serotonin (a neurotransmitter), niacin and auxin (a phytohormone). Tryptophan is a routine constituent of most protein-based foods or dietary proteins. It particularly is plentiful in foods such as, for example, chocolate, oats, durians, mangoes, dried dates, milk, yogurt, cottage cheese, red meat, eggs, fish, poultry, sesame, chickpeas, sunflower seeds, pumpkin seeds, spirulina, and peanuts.
Threonine
Threonine (Thr, T) is an essential amino acid for humans. It promotes normal growth by helping to maintain the proper protein balance in the body. It also supports the cardiovascular, liver, immune and central nervous systems. Threonine is plentiful in foods such as, for example, cottage cheese, poultry, fish, meat, lentils and sesame seeds.
Isoleucine
Isoleucine (Ile, I) is an essential amino acid for humans. Isoleucine promotes muscle recovery after physical exercise and functions in, for example, the formation of hemoglobin, blood sugar regulation, and blood clot formation.
Leucine
Leucine (Leu, L) is an essential amino acid for humans. Leucine, when provided as a dietary supplement to aged rats, has been reported to slow the degradation of muscle tissue by increasing the synthesis of muscle proteins. Leucine is utilized in the liver, adipose tissue, and muscle tissue. In adipose and muscle tissue, leucine is used in the formation of sterols, and the combined usage of leucine in these two tissues is seven-fold greater than its use in the liver. Leucine toxicity may cause delirium, and neurologic compromise.
Lysine
Lysine (Lys, K) is an essential amino acid for humans; it is the limiting amino acid (meaning the essential amino acid found in the smallest quantity in a particular foodstuff) in all cereal grains, but is plentiful in all legumes. Foods that contain significant amounts of lysine include, but are not limited to, red meat, eggs, soybean, lentil, spinach, buckwheat, and other foods rich in protein.
Methionine
Methionine (Met, M) is an essential amino acid for humans. Methionine is an intermediate in the biosynthesis of cysteine, carnitine, taurine, lecithin, phosphatidylcholine, and other phospholipids, and is used in a variety of biochemical pathways. Improper conversion of methionine can lead to atherosclerosis. High levels of methionine can be found in sesame seeds, Brazil nuts, fish, meats, and some other plant seeds. Most fruits and vegetables contain very little methionine.
Cysteine
Cysteine (Cys, C) is a nonessential amino acid. The thiol group of cysteine, because of its high reactivity, has numerous biological functions. If a sufficient quantity of methionine is available, cysteine usually can be synthesized by the human body under normal physiological conditions. Cysteine is found in most high-protein foods including, but not limited to, pork, chicken, turkey, duck, eggs, milk, onions, broccoli, and oats.
Phenylalanine
Phenylalanine (Phe, F) is an essential amino acid for humans. L-phenylalanine is biologically converted into L-tyrosine, which in turn is converted to L-3,4-dihydrooxyphenylalanine (L-DOPA), which is further converted into catecholamines, such as dopamine, norepinephrine and epinephrine. Phenylalanine is found naturally in the breast milk of mammals.
Tyrosine
Tyrosine (Tyr, Y) is a nonessential amino acid that can be synthesized in the body from the essential amino acid phenylalanine and may be found in many proteins that are part of signal transduction processes. It functions as a receiver of phosphate groups that are transferred to a target protein by way of protein kinases. Phosphorylation of the hydroxyl group of tyrosine changes the activity of the target protein. Tyrosine is a precursor to neurotransmitters and increases plasma neurotransmitter levels (particularly dopamine and norepinephrine). Tyrosineis found in many high protein food products, such as, but not limited to, soy products, chicken, turkey, fish, peanuts, almonds, avocados, bananas, milk, cheese, and yogurt.
Valine
Valine (Val, V) is an essential amino acid for humans. Valine has a stimulating effect and is needed for muscle metabolism, repair and growth of tissue, and maintaining the nitrogen balance in the body. Dietary sources include, but are not limited to, cottage cheese, fish, poultry, peanuts, sesame seeds, and lentils.
Arginine
Arginine (Mg, R) is a conditionally nonessential amino acid for humans, meaning that most of the time it can be manufactured by the human body, and does not need to be obtained directly through the diet. Because the biosynthetic pathway does not produce sufficient arginine, some arginine must be consumed through diet. Arginine has an important role in cell division, in the healing of wounds, in removing ammonia from the body, in immune function, and in the release of hormones. Dietary sources of arginine include, but are not limited to, dairy products, beef, pork, poultry, peanuts, nuts, seeds, oatmeal, wheat germ and flour, and chick peas.
Histidine
Histidine (His, H), which is considered an essential amino acid in human infants, is a precursor for histamine and carnosine biosynthesis. It plays a role in the growth and repair of tissue, in the maintenance of myelin sheaths, and in the production of red and white blood cells. Dietary sources of histidine include, but are not limited to, dairy, meat, poultry, fish, rice, wheat and rye.
Alanine
Alanine (Ala, A) is a nonessential amino acid. It has an important role in the glucose/alanine cycle between tissues and liver, which enables pyruvate and glutamate to be removed from muscle and to find their way to the liver. Glucose is regenerated from pyruvate and then returned to muscle. Dietary sources of alanine include, but are not limited to, meat, seafood, dairy products, eggs, fish, beans, nuts, soy, seeds, legumes and whole grains.
Aspartic Acid
Aspartic acid (Asp, D) is a nonessential amino acid that plays a role in the biosynthesis of inositol, the precursor to the purine bases. The carboxylate anion of aspartic acid, aspartate, is a metabolite in the urea cycle and participates in gluconeogenesis. Dietary sources of aspartic acid include, but are not limited to, meat, sprouting seeds, oat flakes, avocado, and asparagus.
Glutamic Acid
Glutamic acid (Glu, E) is a nonessential amino acid. The carboxylate anions and salts of glutamic acid are known as “glutamates.” Glutamate is a key molecule in cellular metabolism. Further, glutamate is the most abundant excitatory neurotransmitter in the vertebrate nervous system. Due to its role in synaptic plasticity, glutamate is involved in cognitive functions such as learning and memory in the brain. Dietary sources of glutamic acid include, but are not limited to, meats, poultry, fish, eggs, and diary products.
Glycine
Glycine (Gly, G) is a nonessential amino acid. Glycine plays a role as a constituent of purines and as an inhibitory neurotransmitter in the central nervous system. Dietary sources of glycine include high-protein foods such as, but not limited to, fish, meat, beans, and dairy products.
Proline
Proline (Pro, P) is an essential amino acid for humans. Proline is biosynthetically derived from L-glutamate. Proline improves skin texture and aids collagen formation. Dietary sources of proline include, but are not limited to, meats.
Serine
Serine (Ser, S) is a nonessential amino acid. Serine plays a role in the biosynthesis of purines and pyrimidines, and is the precursor to several amino acids (including glycine and cysteine), sphingolipids, and folate. Serine also plays a role in the catalytic function of many enzymes including, but not limited to, chymotrypsin and trypsin. Dietary sources of serine include, but are not limited to, meats, dairy products, soy products, and peanuts.
Vitamins and Minerals
Vitamins
The term “vitamin” as used herein, refers to any of various organic substances essential in minute quantities to the nutrition of most animals act especially as coenzymes and precursors of coenzymes in the regulation of metabolic processes. Vitamins have diverse biochemical functions, including function as hormones (for example, vitamin D), antioxidants {for example, vitamin C and vitamin E), and mediators of cell signaling, regulation of cell growth, tissue growth and differentiation (for example, vitamin A). The largest number of vitamins, the B complex vitamins, which is the largest in number, function as precursors for enzyme cofactor biomolecules (co-enzymes) that help act as catalysts and substrates in metabolism.
Vitamin A
The term Vitamin A refers to a group of compounds that play an important role in vision, bone growth, reproduction, cell division, and cell differentiation. In general, there are two categories of vitamin A, depending on whether the food source is an animal or plant.
Vitamin A found in foods that come from animals is referred to as “pre-formed vitamin A.” It is absorbed in the form of retinol, one of the most active forms of vitamin A. Sources include, but are not limited to, liver and whole milk Retinol can be further converted to retinal and retinoic acid.
Vitamin A that is found in colorful fruits and vegetables is referred to as “provitamin A carotenoid,” which can be converted to retinol. In the U.S., approximately 26% of vitamin A consumed by men and 34% of vitamin A consumed by women is in the form of provitamin A carotenoids. Common provitamin A carotenoids found in foods that come from plants are beta (β)-carotene, alpha (α)-carotene and beta (β)-cryptoxanthin. Among these, beta (β)-carotene is most efficiently converted to retinol. Of the 563 identified carotenoids, fewer than 10% can be made into vitamin A in the body. Lycopene, lutein and zeaxanthin are carotenoids that do not have vitamin A activity but that have other health promoting properties. The Institutes of Medicine encourages consumption of all carotenoid-rich fruits and vegetables for their health-promoting benefits.
Retinol is found in foods derived from animals such as, but not limited to, whole eggs, milk, and liver. Most fat-free milk and dried nonfat milk solids sold in the U.S. are fortified with vitamin A to replace the amount lost when the fat is removed. Provitamin A carotenoids are abundant in darkly colored fruits and vegetables. The 2000 National Health and Nutrition Examination Survey (NHANES) indicated that major dietary contributors of retinol are milk, margarine, eggs, beef liver and fortified breakfast cereals, whereas major contributors of provitamin A carotenoids are carrots, cantaloupes, sweet potatoes, and spinach.
Vitamin A in foods derived from animals is well absorbed and used efficiently by the body. Vitamin A in foods derived from plants is not as well absorbed as are animal sources of vitamin A.
Dietary animal sources of vitamin A include, but are not limited to, liver (beef), liver {chicken), milk and cheese. Dietary plant sources of vitamin A (from beta (β)-carotene) include, but are not limited to, carrot juice, carrots, spinach, kale, cantaloupe, apricots, papaya, mango, peas, peaches and tomato juice.
Recommendations for vitamin A are provided in the DRIs developed by the Institute of Medicine (TOM). Table 2 shows the RDAs for vitamin A.
TABLE 2Recommended Dietary Allowances for Vitamin ARecommended Dietary Allowances for Vitamin AAgeChildrenMalesFemalesPregnancyLactation(years)(μg RAE)(μg RAE)(μg RAE)(μg RAE)(μg RAE)1-3300(1000 IU)4-8400(1320 IU) 9-13600(2000 IU)14-189007007501200(3000 IU)(2310 IU)(2500 IU)(4000 IU)19+9007007701300(3000 IU)(2310 IU)(2565 IU)(4300 IU)
Insufficient information is available to establish an RDA for vitamin A for infants. Instead, AIs have been established based on the amount of vitamin A consumed by healthy infants fed breastmilk. AIs for vitamin A for infants aged 0 months to 6 months is 400 (1320 IU) and for those aged 7 months to 12 months is 500 (1650 IU).
The NHANES III survey (1988-1994) found that most Americans consume recommended amounts of vitamin A. More recent NHANES data (1999-2000) show average adult intake to be about 3,300 IU per day.
There is no RDA for beta (β)-carotene or other provitamin A carotenoids. The 10M states that consuming 3 mg to 6 mg of beta (β)-carotene daily (equivalent to 833 IU to 1,667 IU vitamin A) will maintain blood levels of beta (β)-carotene in the range associated with a lower risk of chronic diseases. A diet that provides five or more servings of fruits and vegetables per day and includes some dark green and leafy vegetables and deep yellow or orange fruits should provide sufficient beta (β)-carotene and other carotenoids.
Vegetarians who do not consume eggs and dairy foods need provitamin A carotenoids to meet their need for vitamin A. They should include a minimum of five servings of fruits and vegetables in their daily diet and regularly choose dark green leafy vegetables and orange and yellow fruits to consume recommended amounts of vitamin A.
Vitamin B
The Vitamin B complex is an important group of water-soluble vitamins that participate in many chemical reactions in the body.
Thiamine
Thiamine (vitamin B 1) plays a role in converting carbohydrates into energy, and is essential for the functioning of the heart, muscles, and nervous system.
Thiamine is found in products such as, but not limited to, fortified breads, cereal, pasta, whole grains (especially wheat germ), lean meats (especially pork), fish, dried beans, peas, and soybeans. Dairy products, fruits, and vegetables are not very high in thiamine, but when consumed in large amounts, they become a significant source.
A deficiency of thiamine can cause weakness, fatigue, psychosis, and nerve damage. Thiamine deficiency in the U.S. often is seen in those who abuse alcohol. Brain damage may occur in severe thiamine deficiency. Table 3 shows the Food and Nutrition Board recommendations for dietary intake for thiamine. Specific recommendations for each vitamin depend on age, gender, and other factors (such as pregnancy). Adults, pregnant and lactating women need higher levels of thiamine than young children.
TABLE 3Recommended Dietary Intake for ThiamineRecommended Dietary Intake for Thiamine (mg/day)Infants0-6 months0.27-12 months0.3Children1-3 years0.54-8 years0.69-13 years0.9Adolescents and AdultsMales age 14 and older1.2Females age 14-18 years1.0Females age 19 and older1.1Riboflavin
Riboflavin (vitamin B2) works with other B vitamins and plays a role in body growth, red blood cell production, and assists in releasing energy from carbohydrates.
Dietary food sources of riboflavin include, but are not limited to, lean meats, eggs, legumes, nuts, green leafy vegetables, and dairy products. Breads and cereals often are fortified with riboflavin.
Symptoms of significant deficiency syndromes include sore throat, swelling of mucous membranes, mouth or lip sores, anemia, and skin disorders.
Table 4 shows the Food and Nutrition Board recommendations for dietary intake for riboflavin. Specific recommendations for each vitamin depend on age, gender, and other factors (such as pregnancy). Adults, pregnant and lactating women need higher levels of thiamine than young children.
TABLE 4Recommended Dietary Intake for RiboflavinRecommended Dietary Intake for Riboflavin (mg/day)Infants0-6 months0.37-12 months0.4Children1-3 years0.54-8 years0.69-13 years0.9Adolescents and AdultsMales age 14 and older1.3Females age 14-18 years1.0Females age 19 and older1.1Niacin
Niacin (vitamin B3) assists in the functioning of the digestive system, skin, and nerves, and is important for the conversion of food to energy.
Niacin is in various products including, but not limited to, dairy products, poultry, fish, lean meats, nuts, and eggs. Legumes and enriched breads and cereals also supply some niacin. A deficiency in niacin may lead to pellagra, whose symptoms include inflamed skin, digestive problems, and mental impairment. Large doses of niacin may cause liver damage, peptic ulcers, and skin rashes; even normal doses of niacin may be associated with skin flushing.
Table 5 shows the Food and Nutrition Board recommendations of dietary intake for niacin. Specific recommendations for each vitamin depend on age, gender, and other factors (such as pregnancy). Adults, pregnant and lactating women need higher levels of thiamine than young children.
TABLE 5Recommended Dietary Intake for NiacinRecommended Dietary Intake for Niacin (mg/day)Infants0-6 months2.07-12 months4.0Children1-3 years6.04-8 years8.09-13 years12.0Adolescents and AdultsMales age 14 and older16.0Females age 14-18 years14.0Pantothenic Acid
Pantothenic acid (vitamin B5) is essential to growth and have important roles in metabolism. They are found in foods that are good sources of B vitamins including, but not limited to, eggs, fish, milk and milk products, whole-grain cereals, legumes, yeast, broccoli and other vegetables in the cabbage family, white and sweet potatoes, and lean beef.
Table 6 shows the Food and Nutrition Board recommendations of dietary intake for pantothenic acid. Specific recommendations for each vitamin depend on age, gender, and other factors (such as pregnancy). Adults, pregnant and lactating women need higher levels of thiamine than young children.
TABLE 6Recommended Dietary Intake for Pantothenic AcidRecommended Dietary Intake for Pantothenic Acid (mg/day)Infants0-6 months1.77-12 months1.8Children1-3 years24-8 years39-13 years4Adolescents and Adults14 and older5Vitamin B6
Vitamin B6 is a water-soluble B vitamin that exists in three major chemical forms: pyridoxine, pyridoxal, and pyridoxamine. Pyridoxal phosphate (PLP) is the active form and is a cofactor in many reactions of amino acid metabolism, including transamination, deamination, and decarboxylation. PLP also is necessary for the enzymatic reaction governing the release of glucose from glycogen. Vitamin B6 is involved in various biological processes, including, but not limited to, amino acid, glucose and lipid metabolism, neurotransmitter synthesis, histamine synthesis, hemoglobin synthesis and function, and gene expression. It is found in a wide variety of foods including, but not limited to, beans, meat, poultry, fish, and some fruits and vegetables. More specifically, such foods include, but are not limited to, potato, banana, Garbanzo beans, chicken, pork, beef, trout, sunflower seeds, spinach, tomato juice, avocado, salmon, tuna, peanuts, walnuts, soybean, and lima beans. Table 7 shows the RDAs for vitamin B6 in adults.
TABLE 7Recommended Dietary Allowance for Vitamin B6 for AdultsRecommended Dietary Allowance for Vitamin B6 for AdultsLife-stageMenWomenPregnancyLactationAges 19-501.3 mg1.3 mgAges 51+1.7 mg1.5 mgAll Ages1.9 mg2.0 mg
Results of two national surveys, the National Health and Nutrition Examination Survey (NHANES III 1988-94) and the Continuing Survey of Food Intake by Individuals (1994-96 CSFII), indicated that diets of most Americans meet current intake recommendations for vitamin B6.
Clinical signs of vitamin B6 deficiency are seen rarely in the United States. Many older Americans, however, have low blood levels of vitamin B6, which may suggest a marginal or sub-optimal vitamin 136 nutritional status. Vitamin B6 deficiency may occur in individuals with poor quality diets that are deficient in many nutrients. Symptoms occur during later stages of deficiency, when intake has been very low for an extended time. Signs of vitamin Bb deficiency include dermatitis (skin inflammation), glossitis (a sore tongue), depression, confusion, and convulsions. Vitamin B6 deficiency also can cause anemia. Some of these symptoms also can result from a variety of medical conditions other than vitamin B6 deficiency. It is important that a physician evaluate symptoms so that appropriate medical care can be given.
Vitamin B12
Vitamin B12 (cobalamin) plays a key role in the normal functioning of the brain and nervous system, and in formation of blood. The term “Vitamin B12” refers to a class of chemically-related compounds, all of which have vitamin activity. Structurally the most complicated vitamin, it contains the biochemically rare element cobalt. Vitamin B12 normally is involved in the metabolism of every cell of the body; it affects DNA synthesis and regulation and also fatty acid synthesis and energy production.
Vitamin B12 is found naturally in animal products, including, but not limited to, fish, meat, poultry, eggs, milk, and milk products. Vitamin B12 generally is not found in plant foods. Food sources of vitamin B12 include, but are not limited to, liver (beef), clams, trout, salmon, haddock, tuna, milk, cheese, pork and egg.
Intake recommendations for vitamin B12 and other nutrients are provided in the DRIB developed by the Food and Nutrition Board (FNB) at the Institute of Medicine (TOM) of the National Academies. Table 8 shows the RDAs for vitamin B12. For infants aged 0 months to 12 months, the FNB established an AI for vitamin B12 that is equivalent to the mean intake of vitamin B12 in healthy, breastfed infants.
TABLE 8Recommended Dietary Allowances for Vitamin B12Recommended Dietary Allowances for Vitamin B12AgeMale (μg)Female (μg)Pregnancy (μg)Lactation (μg)0-6 months0.40.47-12 months0.50.51-3 years0.90.94-8 years1.21.29-13 years1.81.814+ years2.42.42.62.8
Daily values (DVs) were developed by the U.S. Food and Drug Administration (FDA) to help consumers determine the level of various nutrients in a standard serving of food in relation to their approximate requirement for it. The DV for vitamin B12 is 6 pg. However, the FDA does not require food labels to list vitamin B12 content unless a food has been fortified with this nutrient.
According to analyses of data from the 1988-1994 National Health and Nutrition Examination Survey (NHANES III) and the 1994-1996 Continuing Survey of Food Intake by Individuals, most children and adults in the U.S. consume recommended amounts of vitamin B 12. Data from the 1999-2000 NHANES indicate that the median daily intake of vitamin B12 for the U.S. population is 3.4 μg.
Some people, particularly older adults, those with pernicious anemia, and those with reduced levels of stomach acidity (achlorhydria) or intestinal disorders, have difficulty absorbing vitamin B12 from food and, in some cases, oral supplements. As a result, vitamin B12 deficiency is common, affecting between 1.5% and 15% of the general population. The cause of the vitamin B12 deficiency remains unknown in many of these cases.
Evidence from the Framingham Offspring Study suggests that the prevalence of vitamin B12 deficiency in young adults might be greater than previously assumed. This study reported that the percentage of participants in three age groups (26 years to 49 years, 50 years to 64 years, and 65 years and older) with deficient blood levels of vitamin B12 was similar.
Vitamin C
Vitamin C (ascorbic acid) is a water-soluble vitamin necessary for normal growth and development. It is required for the growth and repair of tissues in all parts of the body, and is involved in several biological processes including, but not limited to, the formation of collagen, scar tissue, tendons, ligaments, blood vessels, the healing of wounds, and the repair and maintenance of cartilage, bones, and teeth.
Vitamin C is an antioxidant. Antioxidants are nutrients that block some of the damage caused by free radicals. Free-radical damage may contribute to the aging process, cancer, heart disease and other inflammatory conditions, such as, for example, arthritis.
All fruits and vegetables contain some amount of vitamin C. Foods that tend to be the highest sources of vitamin C include green peppers, citrus fruits and juices, strawberries, tomatoes, broccoli, turnip greens, and other leafy greens, sweet and white potatoes, and cantaloupe. Other sources include, but are not limited to, papaya, mango, watermelon, brussel sprouts, cauliflower, cabbage, winter squash, red peppers, raspberries, blueberries, cranberries, and pineapples.
Amounts of Vitamin C greater than 2000 mg/day are not recommended because such high doses may lead to stomach upset and diarrhea. Vitamin C deficiency signs and symptoms include, but are not limited to, dry and splitting hair, gingivitis, rough and dry skin, decreased wound-healing rate, easy bruising, nosebleeds, weakened tooth enamel, swollen and painful joints, anemia, and scurvy.
It is recommended that Vitamin C be consumed every day since it is not fat-soluble and cannot be stored. Table 9 shows the Food and Nutrition Board at the Institute of Medicine recommendations of dietary intake of vitamin C.
TABLE 9Recommended Dietary Intake for Vitamin CRecommended Dietary Intake for Vitamin C (mg/day)Infants and Children0-6 months407-12 months501-3 years154-8 years259-13 years45AdolescentsGirls 14-18 years65Boys 14-18 years75AdultsMen age 19 and older90Women age 19 and older759-13 years45Vitamin D
The term “Vitamin D” refers to a group of fat-soluble prohormones, the two major forms of which are vitamin D2 (ergocalciferol) and vitamin D3 (cholecalferol), their metabolites and functional analogs. Vitamin D obtained from food and supplements is biologically inert and must undergo two hydroxylation reactions to be activated in the body. Calcitriol is the active form of vitamin D found in the human body.
Calcitriol plays an important role in the maintenance of several organ systems. It plays a major role in increasing the flow of calcium into the bloodstream by promoting absorption of calcium and phosphorous from food in the intestines andreabsorption of calcium in the kidneys, by enabling normal mineralization of bone and by preventing hyocalcemic tetany.
Very few foods in nature contain vitamin D. The flesh of fish (such as, for example, salmon, tuna, and mackeral) and fish liver oils are among the best sources. Small amounts of vitamin D are found in beef liver, cheese, and egg yolks. Vitamin Din these foods is primarily in the form of vitamin D2. Some mushrooms provide vitamin D2 in variable amounts.
Fortified foods provide most of the vitamin D in the American diet. For example, almost all of the U.S. milk supply is fortified with 100 IU/cup of vitamin D (25% of the DV or 50% of the AI level for ages 14 years to 50 years). In the U.S., foods allowed to be fortified with vitamin D include cereal flours and related products, milk, and products made from milk, and calcium-fortified fruit juices and drinks.
DVs were developed by the U.S. Food and Drug Administration to help consumers compare the nutrient contents of products within the context of a total diet. The DV for vitamin D is 400 IU for adults and children age 4 and older. Food labels, however, are not required to list vitamin D content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.
Intake recommendations for vitamin D and other nutrients are provided in the DRIs developed by the Food and Nutrition Board (FNB) at the Institute of Medicine (TOM) of the National Academies. The FNB established an AI for vitamin D that represents a daily intake sufficient to maintain bone health and normal calcium metabolism in healthy people. Table 10 shows the AIs for vitamin D; the AIs for vitamin D are based on the assumption that the vitamin is not synthesized by exposure to sunlight. The biological activity of 1 pg is equal to 40 IU.
TABLE 10Adequate Intake for Vitamin D.Adequate Intake for Vitamin DAgeChildrenMenWomenPregnancyLactationBirth to 135 μgyears(200 IU)14-18 years 5 μg 5 μg5 μg5 μg(200 IU)(200 IU)(200 IU)(200 IU)19-50 years 5 μg 5 μg5 μg5 μg(200 IU)(200 IU)(200 IU)(200 IU)51-70 years10 μg10 μg(200 IU)(200 IU)71+ years15 μg15 μg(200 IU)(200 IU)
In 2008, the American Academy of Pediatrics (AAP) issued recommended intake values for vitamin D that exceed those of FNB. The AAP recommendations are based on evidence from more recent clinical trials and the history of safe use of 400 IU/day of vitamin D in pediatric and adolescent populations. AAP recommends that exclusively and partially breastfed infants receive supplements of 400 IU/day of vitamin D shortly after birth and continue to receive these supplements until they are weaned and consume greater than 1,000 mL/day of vitamin D-fortified formula or whole milk. (All formulas sold in the United States provide greater than 400 III vitamin D3 per liter, and the majority of vitamin D-only and multivitamin liquid supplements provide 400 IU per serving). Similarly, all non-breastfed infants ingesting less than 1,000 mL/day of vitamin D-fortified formula or milk should receive a vitamin D supplement of 400 IU/day. AAP also recommends that older children and adolescents who do not obtain 400 IU/day through vitamin D-fortified milk and foods should take a 400 IU vitamin D supplement daily.
Vitamin E
Vitamin E is a generic term for tocopherols and tocotrienols; it describes a family of α-, β-, γ- and δ-tocopherols and corresponding four tocotrienols. Vitamin E is a fat-soluble antioxidant that stops the production of reactive oxygen species formed when fat undergoes oxidation. Of these, α-tocopherol has the highest bioavailability.
Dietary sources of vitamin E include asparagus, avocado, egg, milk, nuts (almonds and hazelnuts), seeds, spinach and vegetable oils. Most vitamin E in American diets is in the form of 5-tocopherol from soybean, canola, corn, and other vegetable oils and food products.
Intake recommendations for vitamin E and other nutrients are provided in the DRIs developed by the Food and Nutrition Board (FNB) at the Institute of Medicine (TOM) of the National Academies. The FNB's vitamin E recommendations are for α-tocopherol alone, the only form maintained in plasma. The FNB based these recommendations primarily on serum levels of the nutrient that provide adequate protection in a test measuring the survival of erythrocytes when exposed to hydrogen peroxide. In acknowledging “great uncertainties” in these data, the FNB has called for research to identify other biomarkers for assessing vitamin E requirements. Table 11 shows RDA for vitamin E. Because insufficient data are available to develop RDAs for infants, AIs were developed based on the amount of vitamin E consumed by healthy breastfed babies.
TABLE 11Recommended Dietary Allowances for Vitamin E (α-tocopherol.Recommended Dietary Allowances for Vitamin E (α-tocopherol)AgeMalesFemalesPregnancyLactationBirth to 6 months4 mg4 mgN/AN/A  (6 IU)  (6 IU)7-12 months5 mg5 mgN/AN/A (7.5 IU) (7.5 IU)1-3 years6 mg6 mgN/AN/A  (9 IU)  (9 IU)4-8 years7 mg7 mgN/AN/A(10.4 IU)(10.4 IU)9-13 years11 mg 11 mg N/AN/A(16.4 IU)(16.4 IU)14+ years15 mg 15 mg 15 mg15 mg(22.4 IU)(22.4 IU)(22.4 IU)(22.4 IU)
DVs were developed by the U.S. Food and Drug Administration (FDA) to help consumers compare the nutrient content of different foods within the context of a total diet. The DV for vitamin E is 30 IU (approximately 20 mg of natural a-tocopherol) for adults and children age 4 and older. However, the FDA does not require food labels to list vitamin E content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient, but foods providing lower percentages of the DV also contribute to a healthful diet.
Vitamin K
Vitamin K (phytonadione) is a fat-soluble vitamin that plays an important role in blood clotting.
Vitamin K is found in cabbage, cauliflower, spinach, and other green leafy vegetables, cereals, soybeans, and other vegetables. Vitamin K also is made by the bacteria that line the gastrointestinal tract.
Individuals with vitamin K deficiency usually are more likely to have bruising and bleeding.
Table 12 shows the recommendations of the Food and Nutrition Board at the Institute of Medicine of dietary intake for vitamin K. Specific recommendations for each vitamin depend on age, gender, and other factors (such as pregnancy). Adults, pregnant and lactating women need higher levels of thiamine than young children.
TABLE 12Recommended Dietary Intake for Vitamin K.Recommended Dietary Intake for Vitamin K (μg/day)Infants0-6 months2.07-12 months2.5Children1-3 years304-8 years559-13 years60Adolescents and Adults14 to 18 years7519 and older90Minerals.
Minerals are inorganic elements that are essential constituents of cells. For example, humans cannot produce calcium, which therefore must be absorbed through the diet.
Calcium
Calcium (Ca) the most abundant mineral in the body, plays a role in muscle contraction, in blood vessel expansion and contraction, in secretion of hormones and enzymes, and in transmitting impulses throughout the nervous system. It is found in some foods, is added to others, is available as a dietary supplement, and is present in some medicines (such as, for example, antacids). The human body strives to maintain constant concentrations of calcium in blood, muscle, and intracellular fluids, though less than 1% of total body calcium is needed to support these functions. The remaining 99% of the body's calcium is stored in the bones and teeth where it supports their structure.
Intake recommendations for calcium and other nutrients are provided in the DRIs developed by the Food and Nutrition Board (FNB) at the U.S. Institute of Medicine of the National Academies. DRI is the general term for a set of reference values used for planning and assessing the nutrient intake of healthy individuals. These values, which vary by age and gender, include (1) the recommended daily allowance (RDA), which is the average daily level of intake sufficient to meet the nutrient requirements of nearly all (97-98%) healthy individuals; (2) adequate intake (AI), established when evidence is insufficient to develop an RDA and is set at a level assumed to ensure nutritional adequacy; and (3) tolerable upper intake level (UL), a maximum daily intake unlikely to cause adverse health effects. Table 13 shows the AIs (mg per day) established by the FNB for the amounts of calcium required to maintain adequate rates of calcium retention and bone health in healthy individuals.
TABLE 13Adequate Intakes (mg per day) established by the FNB for theamounts of calcium required to maintain adequate rates ofcalcium retention and bone health in healthy individualsAdequate Intake (AI) for CalciumAgeMaleFemalePregnantLactatingBirth to 6 months210mg210mg7-12 months270mg270mg1-3 years500mg500mg4-8 years800mg800mg9-13 years1300mg1300mg14-18 years1300mg1300mg1300 mg1300 mg19-50 years1000mg1000mg1000 mg1000 mg50+ years1200mg1200mg
Milk, yogurt, and cheese are rich sources of calcium and are the major food contributors of this nutrient to people in the United States. Nondairy sources include vegetables, such as, but not limited to, Chinese cabbage, kale, and broccoli. Most grains do not have high amounts of calcium unless they are fortified; however, grains contribute calcium to the diet because they do have small amounts and people consume them frequently. Foods fortified with calcium include many fruit juices and drinks, tofu, and cereals.
The two main forms of calcium in supplements are carbonate and citrate. Calcium carbonate is more commonly available and is both inexpensive and convenient. Both the carbonate and citrate forms are similarly well absorbed, but individuals with reduced levels of stomach acid can absorb calcium citrate more easily. Other calcium forms in supplements or fortified foods include gluconate, lactate, and phosphate. Calcium citrate malate is a well-absorbed form of calcium found in some fortified juices. The body absorbs calcium carbonate most efficiently when the supplement is consumed with food, whereas the body can absorb calcium citrate equally effectively when the supplement is taken with or without food.
Calcium supplements contain varying amounts of elemental calcium. For example, calcium carbonate is 40% calcium by weight, whereas calcium citrate is 21% calcium. The percentage of calcium absorbed depends on the total amount of elemental calcium consumed at one time; as the amount increases, the percentage absorption decreases. Absorption is highest in doses less than 500 mg. For example, one who takes 1,000 mg/day of calcium from supplements may split the dose and take 500 mg at two separate times during the day. Because of its biological importance, calcium levels are carefully controlled in various compartments of the body. The three major regulators of blood calcium are parathyroid hormone (PTH), vitamin D, and calcitonin. PTH normally is released by the four parathyroid glands in the neck in response to low calcium levels in the bloodstream (hypocalcemia). PTH acts in three main ways: (1) It causes the gastrointestinal tract to increase calcium absorption from food, (2) it causes the bones to release some of their calcium stores, and (3) it causes the kidneys to excrete more phosphorous, which indirectly raises calcium levels.
Some individuals who take calcium supplements may experience symptoms such as, for example, gas, bloating, constipation, or a combination of these. Such symptoms often can be resolved by spreading out the calcium dose throughout the day, taking the supplement with meals, or changing the brand of supplement used.
Many Americans do not ingest recommended amounts of calcium from food. For example, according to the nationwide Continuing Survey of Food Intake of Individuals, approximately 44% of boys and 58% of girls aged 6-11 fell short in 1994-1996, as did 64% of boys and 87% of girls aged 12-19 years and 55% of men and 78% of women aged 20 years or older. The National Health and Nutrition Examination Survey (1999-2000) reported that average calcium intake were 1,081 and 793 mg/day for boys and girls ages 12-19 years, respectively; 1,025 and 797 mg/day for men and women 20-39 years; and 797 and 660 mg/day for men and women >60 years. Overall, females are less likely than males to get the recommended intake of calcium from food.
Most dietary calcium is absorbed in the small intestine. Vitamin D, which works together with PTH on bone and the kidney, is necessary for intestinal absorption of calcium. Not all calcium consumed is actually absorbed in the gut. Factors that affect absorption include, but are not limited to, (1) amount consumed, the efficiency of absorption decreases as the amount of calcium consumed at a meal increases; (2) age, net calcium absorption is as high as 60% in infants and young children, who need substantial amounts of the mineral to build bone. Absorption decreases to 15%-20% in adulthood and continues to decrease as people age; (3) vitamin D intake; and (4) other components in food; for example, phytic acid and oxalic acid, found naturally in some plants, bind to calcium and can inhibit its absorption. Foods with high levels of oxalic acid include, but are not limited to, spinach, collard greens, sweet potatoes, rhubarb, and beans. Foods high in phytic acid include, but are not limited to, fiber-containing whole-grain products, wheat bran, beans, seeds, nuts, and soy isolates. The extent to which these compounds affect calcium absorption varies. Some studies have reported that eating spinach and milk at the same time reduces absorption of the calcium in milk. In contrast, wheat products (with the exception of wheat bran) do not appear to have a negative impact on calcium absorption. These interactions probably have little or no nutritional consequence for people who eat a variety of food, and, furthermore, are accounted for in the overall calcium DRIs (which take absorption into account).
Some absorbed calcium is eliminated from the body in urine, feces and sweat. The amount eliminated is affected by several factors, including:
(1) sodium, potassium, and protein intake—high intake of sodium and protein increase calcium excretion, while adding more potassium to a high-sodium diet may help decrease calcium excretion, particularly in postmenopausal women.
(2) caffeine intake—caffeine may modestly increase calcium excretion and reduce absorption. For example, one cup of regular brewed coffee causes a loss of only 2 mg to 3 mg of calcium. Moderate caffeine consumption (1 cup of coffee or 2 cups of tea per day) in young women has no negative effects on bone.
(3) alcohol intake—alcohol intake may affect calcium status by reducing its absorption and by inhibiting enzymes in the liver that help convert vitamin D to its active form, however, the amount of alcohol required to affect calcium status and the effect of moderate alcohol consumption on bone loss is unknown.
(4) phosphorus intake—the effect of this mineral on calcium excretion is minimal.
(5) fruit and vegetable intake—these foods, when metabolized, shift the acid/base balance of the body towards the alkaline by producing bicarbonate, which reduces calcium loss. For example, metabolic acids produced by diets high in protein and cereal grains cause bone to release minerals such as calcium, phosphates, and alkaline salts that neutralize the excess acid.
Inadequate intake of dietary calcium from food and supplements produce no obvious symptoms in the short term. Hypocalcemia results primarily from medical problems or treatments, including renal failure, surgical removal of the stomach, and use of certain medications (such as diuretics). Symptoms of hypocalcemia may include numbness and tingling in the fingers, muscle cramps, convulsions, lethargy, poor appetite, and abnormal heart rhythms; if left untreated, calcium deficiency may lead to death.
Chromium
Chromium (Cr) is a mineral that humans require in trace amounts; its mechanism of action in the body and the amounts of chromium needed for optimal health are not well defined. Chromium is found primarily in two forms: I) trivalent (Cr3+), which is biologically active and found in food; and 2) hexavalent (Cr6), a toxic form that results from industrial pollution.
It generally is believed that chromium enhances the action of insulin, a hormone critical to the metabolism and storage of carbohydrate, fat, and protein in the body. Studies in animal models have reported that chromium prevents an age-related decline in the ability of rats to maintain normal levels of sugar (glucose) in their blood. Chromium also is believed to be directly involved in carbohydrate, fat, and protein metabolism.
Chromium is widely distributed in the food supply, but most foods provide only small amounts (less than 2 lig/serving). Meat and whole-grain products, as well as some fruits (such as, but not limited to, bananas, grape juice, red wine, apples, orange juice), vegetables (such as, but not limited to, broccoli, potatoes, green beans), and spices (such as, but not limited to, garlic and basil) are relatively good sources. In contrast, foods high in simple sugars (such as, but not limited to, sucrose and fructose) are low in chromium.
Dietary intake of chromium cannot be determined reliably because the content of the mineral in foods is affected substantially by agricultural and manufacturing processes and perhaps by contamination with chromium when the foods are analyzed. Subsequently, food-composition databases generally provide approximate values of chromium in foods and serve only as a guide.
The U.S. National Academy of Sciences has established an estimated safe and adequate daily dietary intake range for chromium. Since the research base was insufficient to establish RDAs, chromium adequate intake (AI) values have been developed based on average intake of chromium from food as reported in several studies. Chromium AIs are provided in Table 14.
TABLE 14Adequate Intake (AIs) for ChromiumAdequate Intake (AIs) for ChromiumInfants andChildrenMalesFemalesPregnancyLactationAge(μg/day)(μg/day)(μg/day)(μg/day)(μg/day)0 to 6 months0.27 to 12 months5.51 to 3 years114 to 8 years159 to 13 years252114 to 18 years3524294419 to 50 years35253045>50 years3020
Adult women in the United States consume about 23 to 29 μg of chromium per day from food, which meets their AIs unless they are pregnant or lactating. In contrast, adult men average 39 to 54 μg per day, which exceeds their AIs. The average amount of chromium in the breast milk of healthy, well-nourished mothers is 0.24 μg per quart; infants exclusively fed breast milk obtain about 0.2 μg (based on an estimated consumption of 0.82.quarts per day). Infant formula provides about 0.5 μg of chromium per quart. Few studies have compared how well infants absorb and utilize chromium from human milk and from formula.
There is little absorption of chromium from the intestinal tract (ranging from less than 0.4% to 2.5% of the amount consumed), and the remainder is excreted in the feces. Vitamin C (found in fruits and vegetables and their juices) and the B vitamin niacin (found in meats, poultry, fish, and grain products) enhance chromium absorption. The body's chromium content may be reduced under several conditions. Diets high in simple sugars (comprising more than 35% of calories) can increase chromium excretion in the urine. Infection, acute exercise, pregnancy and lactation, and stressful states (such as physical trauma) increase chromium losses and can lead to deficiency, especially if chromium intake are already low. Some studies have reported significant age-related decreases in the chromium concentrations of hair, sweat, and blood, which may suggest that older adults are more vulnerable to chromium depletion than younger adults. One caveat is that chromium status is difficult to determine since blood, urine, and hair levels do not necessarily reflect body stores. Furthermore, no chromium-specific enzyme or other biochemical marker has been found to reliably assess a person's chromium status.
Folate
Folate is a water-soluble B vitamin that occurs naturally in food. Folic acid (the synthetic form of folate) is found in supplements and added to fortify foods. Folate plays a role in the production and maintenance of new cells and the synthesis of DNA and RNA. Both adults and children require folate to produce normal red blood cells and prevent anemia. Folate also is essential for the metabolism of homocysteine. Folate has a protective effect against the development of neural tube defects during pregnancy.
The U.S. Food and Drug Administration has published regulations requiring the addition of folic acid to enriched breads, cereals, flours, corn meals, pastas, rice, and other grain products. Since cereals and grains are widely consumed in the U.S., these products have become a very important contributor of folic acid to the American diet. Dietary sources of folate include, but are not limited to, beef liver, cow peas, spinach, Great Northern beans, asparagus, rice, green peas, broccoli, egg noodles, avocado, peanuts, tomato juice, orange juice, turnip greens, orange, eggs, cantaloupe, Papaya, and banana.
Recommendations for folate are given in the DRIs developed by the Institute for Medicine of the National Academy of Sciences. The RDAs for folate are expressed in a term called the “Dietary Folate Equivalent.” The Dietary Folate Equivalent (DFE) was developed to help account for the differences in absorption of naturally occurring dietary folate and the more bioavailable synthetic folic acid. Table 15 lists the RDAs for folate, expressed in micrograms (p,g) of DFE, for children and adults.
TABLE 15Recommended Dietary Allowances for Folate for Children and AdultsRecommended Dietary Allowances for Folate for Children and AdultsMales andAgeFemalesPregnancyLactation(years)(μg/day)(μg/day)(μg/day)1-3150N/AN/A4-8200N/AN/A 9-13300N/AN/A14-1840060050019+400600500
There is insufficient information to establish an RDA for folate for infants. An AI based on the amount of folate consumed by healthy infants who are fed breast milk has been established. The AI for folate for infants aged 0-6 months is 65 μg/day, and for infants aged 7-12 months is 80 μg/day.
The National Health and Nutrition Examination Survey (NHANES III 1988-94) and the Continuing Survey of Food Intake by Individuals (1994-96 CSFII) indicated that most individuals surveyed did not consume adequate folate. However, the folic acid fortification program, which was initiated in 1998, has increased folic acid content of commonly eaten foods such as, for example, cereals and grains, and as a result most diets in the United States now provide recommended amounts of folate equivalents.
A deficiency of folate can occur when an increased need for folate is not matched by an increased intake, when dietary folate intake does not meet recommended needs, and when folate loss increases. Medications that interfere with the metabolism of folate also may increase the need for this vitamin and the risk of deficiency.
It is not unusual to find foods, such as some ready-to-eat cereals, fortified with 100% of the RDA for folate. The variety of fortified foods available has made it easier for women of childbearing age in the US to consume the recommended 400 μg of folic acid per day from fortified foods and/or supplements. The large numbers of fortified foods on the market, however, also raises the risk of exceeding the upper intake levels (UL). This is especially important for anyone at risk of vitamin B12 deficiency, which can be triggered by too much folic acid. It is important for anyone who is considering taking a folic acid supplement to first consider whether their diet already includes adequate sources of dietary folate and fortified food sources of folic acid.
Iron
Iron is an integral part of many proteins and enzymes that maintain good health. In humans, it is an essential component of proteins involved in oxygen transport and is essential for the regulation of cell growth and differentiation. A deficiency of iron limits oxygen delivery to cells, resulting in fatigue, poor work performance, and decreased immunity. Excess amounts of iron can result in toxicity and even death. Almost two-thirds of iron in the body is found in hemoglobin, the protein in red blood cells that carries oxygen to tissues. Smaller amounts of iron are found in myoglobin, a protein that helps supply oxygen to muscle, and in enzymes that assist biochemical reactions.
There are two forms of dietary iron: heme and nonheme. Heme iron is derived from hemoglobin and is found in animal foods that originally contained hemoglobin, such as, for example, red meats, fish, and poultry. Iron in plant foods, such as, for example, lentils and beans, is arranged in a chemical structure called nonheme iron. The nonheme form of iron is added to iron-enriched and iron-fortified foods. Heme iron is absorbed better than nonheme iron, but most dietary iron is nonheme iron. Heme iron sources include, but are not limited to, chicken liver, oysters, beef, clams, beef, turkey, tuna, halibut, crab, pork and shrimp. Nonheme iron sources include, but are not limited to, soybeans, lentils, beans (kidney, lima, navy, black, pinto), molasses, spinach, black-eyed peas, and raisins.
Recommendations for iron are provided in the Dietary Reference Intake (DRIB) developed by the Institute of Medicine of the National Academy of Sciences. Table 16 shows the RDAs for iron (mg) for infants, children and adults.
TABLE 16Recommended Dietary Allowances for Iron for Infants(7 to 12 months), Children, and AdultsRecommended Dietary Allowances for Iron for Infants(7 to 12 months), Children, and AdultsMalesFemalesPregnancyLactationAge(mg/day)(mg/day)(mg/day)(mg/day)7 to 12 months1111N/AN/A1 to 3 years77N/AN/A4 to 8 years1010N/AN/A9 to 13 years88N/AN/A14 to 18 years111519 to 50 years81851+ years88N/AN/A
Healthy full term infants are born with a supply of iron that lasts for 4 months to 6 months after birth. Insufficient evidence is available to establish an RDA for iron for infants from birth through 6 months of age. Recommended iron intake for this age group is based on an Adequate Intake (AI) that reflects the average iron intake of healthy infants fed breast milk. The Al for iron for infants (0 to 6 months) is 0.27 mg/day.
Iron in human breast milk is well absorbed by infants. It is estimated that infants can use more than 50% of the iron in breast milk as compared to less than 12% of the iron in infant formula. The amount of iron in cow's milk is low, and infants poorly absorb it. Additionally, gastrointestinal bleeding may result from feeding cow's milk to infants. For these reasons, cow's milk should not be fed to infants until they are at least 1 year old. The American Academy of Pediatrics (AAP) recommends that (i) infants should be exclusively breast fed for the first six months of life, (ii) gradual introduction of iron-enriched solid foods should complement breast milk from 7 to 12 months of age; and (iii) infants weaned from breast milk before 12 months of age should receive iron-fortified infant formula. Infant formulas that contain from 4 to 12 milligrams of iron per liter are considered iron-fortified.
Data from the National Health and Nutrition Examination Survey (NHANES) describe dietary intake of Americans 2 months of age and older. NHANES (1988-94) data suggest that males of all racial and ethnic groups consume recommended amounts of iron, while iron intake generally is low in females of childbearing age and young children.
Researchers also have examined specific groups within the NHANES population. For example, researchers have compared the dietary intake of adults who consider themselves to be food insufficient (and therefore have limited access to nutritionally adequate foods) to those who are food sufficient (and have easy access to food). Older adults from food insufficient families had significantly lower intake of iron than older adults who are food sufficient. In one survey, 20% of adults age 20 to 59 and 13.6% of adults age 60 and older from food insufficient families consumed less than 50% of the RDA for iron, compared to 13% of adults age 20 to 50 and 2.5% of adults age 60 and older from food sufficient families.
Iron intake is negatively influenced by low nutrient density foods, which are high in calories but low in vitamins and minerals. Sugar sweetened sodas and most desserts are examples of low nutrient density foods, as are snack foods such as potato chips. Some surveys have reported that among almost 5,000 children and adolescents between the ages of 8 and 18 who were surveyed, low nutrient density foods contributed almost 30% of daily caloric intake, with sweeteners and desserts jointly accounting for almost 25% of caloric intake. Those children and adolescents who consumed fewer “low nutrient density” foods were more likely to consume recommended amounts of iron.
Studies have used data from The Continuing Survey of Food Intake by Individuals (CSFII1994-6 and 1998) to examine the effect of major food and beverage sources of added sugars on micronutrient intake of U.S. children aged 6 to 17 years. Researchers reported that consumption of presweetened cereals, which are fortified with iron, increased the likelihood of meeting recommendations for iron intake. Conversely, as intake of sugar-sweetened beverages, sugars, sweets, and sweetened grains increased, children were less likely to consume recommended amounts of iron.
According to the World Health Organization on “Micronutrient Deficiencies” at www.who.int, iron deficiency is the most common and widespread nutritional disorder in the world, affecting more people than any other condition. As many as 80% of the world's population may be iron deficient, while 30% may have iron deficiency anemia. However, there is considerable potential for iron toxicity because very little iron is excreted from the body. Thus, iron can accumulate in body tissues and organs when normal storage sites are full.
Magnesium
Magnesium is the fourth most abundant mineral in the body and is essential to good health. Approximately 50% of total body magnesium is found in bone. The other half is found predominantly inside cells of body tissues and organs, with 1% residing in the blood. Magnesium is involved in maintenance of normal muscle and nerve function, cardiac function, the immune system, blood glucose levels, energy metabolism and protein synthesis.
Dietary sources of magnesium include, but are not limited to, green vegetables, such as spinach, legumes (beans and peas), nuts and seeds, and whole, unrefined grains. Dietary magnesium is absorbed through the small intestines and excreted via the kidneys.
Recommendations for magnesium are provided in the DRIs developed by the Institute of Medicine of the National Academy of Sciences. Table 17 shows the RDAs for magnesium for children and adults.
TABLE 17Recommended Dietary Allowances for Magnesium for Childrenand AdultsRecommended Dietary Allowances for Magnesium for Childrenand AdultsFemalePregnancyLactationAge (years)Male (mg/day)(mg/day)(mg/day)(mg/day)1-38080N/AN/A4-8130130N/AN/A 9-13240240N/AN/A14-1841036040036019-3040031035031031+420320360320
There is insufficient information on magnesium to establish a RDA for infants. Instead, for infants 0 to 12 months, the DRI is in the form of an Adequate Intake (AI), which is the mean intake of magnesium in healthy, breastfed infants. The Ms for infants aged 0 months to 6 months is 30 mg/day; the AI for infants aged 7 months to 12 months is 75 mg/day.
Data from the 1999-2000 National Health and Nutrition Examination Survey suggest that substantial numbers of adults in the United States (US) fail to get recommended amounts of magnesium in their diets. Among adult men and women, the diets of Caucasians have significantly more magnesium than do those of African-Americans. Magnesium intake is lower among older adults in every racial and ethnic group. Among African-American men and Caucasian men and women who take dietary supplements, the intake of magnesium is significantly higher than in those who do not. Even though dietary surveys suggest that many Americans do not get recommended amounts of magnesium, symptoms of magnesium deficiency are seen rarely in the US. However, there is concern that many people may have insufficient body stores of magnesium because dietary intake of magnesium may be insufficient.
Selenium
Selenium is a trace mineral essential to good health but that is required only in small amounts. Selenium is incorporated into proteins to make selenoproteins, which are important antioxidant enzymes. Other selenoproteins help regulate thyroid function and play a role in the immune system. The antioxidant properties of selenoproteins help prevent cellular damage from free radicals. A free radical is a highly reactive and usually short-lived molecular fragment with one or more unpaired electrons. Free radicals are highly chemically reactive molecules. Because a free radical needs to extract a second electron from a neighboring molecule to pair its single electron, it often reacts with other molecules, which initiates the formation of many more free radical species in a self-propagating chain reaction. This ability to be self-propagating makes free radicals highly toxic to living organisms. Oxidative injury may lead to widespread biochemical damage within the cell. The molecular mechanisms responsible for this damage are complex. For example, free radicals may damage intracellular macromolecules, such as nucleic acids (e.g., DNA and RNA), proteins, and lipids. Free radical damage to cellular proteins may lead to loss of enzymatic function and cell death. Free radical damage to DNA may cause problems in replication or transcription, leading to cell death or uncontrolled cell growth. Free radical damage to cell membrane lipids may cause the damaged membranes to lose their ability to transport oxygen, nutrients or water to cells.
Plant foods are the major dietary sources of selenium in most countries throughout the world. The content of selenium in food depends on the selenium content of the soil where plants are grown or animals are raised. For example, researchers have reported that soils in the high plains of northern Nebraska and the Dakotas have very high levels of selenium. People living in those regions generally have the highest selenium intake in the United States. In the U.S., food distribution patterns across the country help prevent people living in low-selenium geographic areas from having low dietary selenium intake. Soils in some parts of China and Russia have very low amounts of selenium; selenium deficiency often is reported in those regions because most food in those areas is grown and eaten locally.
Selenium also can be found in some meats and seafood. Animals that eat grains or plants that were grown in selenium-rich soil have higher levels of selenium in their muscle. In the U.S., meats and bread are common sources of dietary selenium. Some nuts, such as, but not limited to, Brazil nuts, also are sources of selenium.
Recommendations for selenium are provided in the DRIs developed by the Institute of Medicine. Table 18 shows the RDAs for selenium for children and adults.
TABLE 18Recommended Dietary Allowances for Selenium for Children and AdultsRecommended Dietary Allowances for Selenium for Children and AdultsMales and FemalesPregnancyAge (years)(μg/day)(μg/day)Lactation (μg/day)1-3years20N/AN/A4-8years30N/AN/A9-13years40N/AN/A14-18years55607019+years556070
There is insufficient information to establish a RDA for selenium for infants. An AI has been established that is based on the amount of selenium consumed by healthy infants who are fed breast milk. The AI for selenium for infants aged 0 months to 6 months is 15 μg/day; for those aged 7 months to 12 months, the AI is 20 μg/day. Results of the National Health and Nutrition Examination Survey (NHANES 111-1988-94) indicated that the diets of most Americans provide the recommended amounts of selenium. The INTERMAP study examined nutrient intake of almost 5,000 middle-aged men and women in four countries, including the U.S., in the late 1990s. The primary aim of the study was to evaluate the effect of dietary micronutrients on blood pressure. Each study participant completed four, 24-hour dietary recalls, during which they were asked to record everything consumed (food, beverages, and dietary supplements) over the previous 24 hours. Selenium intake was lowest among residents of China, the country with the highest known rate of selenium deficiency. Mean dietary intake of selenium of U.S. participants was 153 μg for men and 109 μg for women. Both values exceed the recommended selenium intake for adults.
Zinc
Zinc is an essential mineral that is naturally present in some foods, added to others, and available as a dietary supplement. Zinc is involved in numerous aspects of cellular metabolism; it is required for the catalytic activity of approximately 100 enzymes, and plays a role in immune function, protein synthesis, wound healing, DNA synthesis, and cell division. A daily intake of zinc is required to maintain a steady state because the body has no specialized zinc storage system.
A wide variety of foods contain zinc, including, but not limited to, oysters, beef, crab, pork, chicken, lobster, cashews, chickpeas, cheese, almonds, milk, flounder, and kidney beans.
Intake recommendations for zinc and other nutrients are provided in the DRIs developed by the Food and Nutrition Board (FNB) at the Institute of Medicine (10M) of the National Academies. Table 19 shows the RDAs for zinc. For infants aged 0 months to 6 months, the FNB established an AI for zinc that is equivalent to the mean intake of zinc in healthy, breastfed infants.
TABLE 19Recommended Dietary Allowances for Zinc.Recommended Dietary Allowances for ZincAgeMalesFemalesPregnancyLactationBirth to 6months2 mg2 mgN/AN/A7 months to 3 years3 mg3 mgN/AN/A4-8years5 mg5 mgN/AN/A9-13years8 mg8 mgN/AN/A14 to 18years11 mg 9 mg13 mg14 mg19+years11 mg 8 mg11 mg12 mg
DVs were developed by the U.S. Food and Drug Administration to help consumers compare the nutrient contents of products within the context of a total diet. The DV for zinc is 15 mg for adults and children age 4 and older. Food labels, however, are not required to list zinc content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.
Most infants (especially those who are formula fed), children, and adults in the United States consume recommended amounts of zinc according to two national surveys, the 1988-1991 National Health and Nutrition Examination Survey (NHANES III) and the 1994 Continuing Survey of Food Intake of Individuals (CSFII). However, some evidence suggests that zinc intake among older adults might be marginal. Studies reported that an analysis of NHANES III data indicates that 35% to 45% of adults aged 60 years or older had zinc intake below the estimated average requirement of 6.8 mg/day for elderly females and 9.4 mg/day for elderly males. When the investigators considered intake from both food and dietary supplements, they reported that 20% to 25% of older adults still had inadequate zinc intake.
Zinc intake might also be low in older adults from the 2% to 4% of U.S. households that are food insufficient (sometimes or often not having enough food). Studies reported that data from NHANES III indicate that adults aged 60 years or older from food-insufficient families had lower intake of zinc and several other nutrients and were more likely to have zinc intake below 50% of the RDA on a given day than those from food-sufficient families.
Phosphorous
Phosphorous is a key element in all known forms of life. Inorganic phosphorous plays a major role in biological molecules such as DNA and RNA, where it forms part of the structural framework of these molecules. Living cells also use phosphate to transport cellular energy in the form of adenosine triphosphate (ATP). Nearly every cellular process that uses energy obtains it in the form of ATP.
Dietary sources of phosphorous include, but are not limited to, meat, poultry, fish, eggs, seeds, milk, broccoli, apples, carrots, asparagus, bran and corn.
Sodium and Potassium
Salt is sodium chloride. Food labels list sodium rather than salt content. Consumers are directed to look for the sodium content when reading a Nutrition Facts Panel on a food product. Foods that are low in sodium (less than 140 mg or 5% of the Daily Value (DV)) are low in salt.
Nearly all Americans consume substantially more salt than they need. On average, the natural salt content of food accounts for only about 10% of total intake, while discretionary salt use (i.e., salt added at the table or while cooking) provides another 5-10% of total intake. Approximately 75% is derived from salt added by manufacturers. In addition, foods served by food establishments may be high in sodium. It is important to read the food label and determine the sodium content of food, which can vary by several hundreds of milligrams in similar foods. For example, the sodium content in regular tomato soup may be 700 mg per cup in one brand and 1100 mg per cup in another brand. Reading labels, comparing sodium contents of foods, and purchasing the lower sodium brand may be one strategy to lower total sodium intake.
Reducing salt intake is one of several ways that people may lower their blood pressure. The relationship between salt intake and blood pressure is direct and progressive without an apparent threshold. On average, the higher a person's salt intake, the higher the blood pressure. Reducing blood pressure, ideally to the normal range, reduces the risk of stroke, heart disease, heart failure, and kidney disease.
Another dietary measure to lower blood pressure is to consume a diet rich in potassium. A potassium-rich diet also blunts the effects of salt on blood pressure, may reduce the risk of developing kidney stones, and possibly decrease bone loss with age. The recommended intake of potassium for adolescents and adults is 4700 mg/day. Potassium should come from food sources. Fruits and vegetables, which are rich in potassium with its bicarbonate precursors, favorably affect acid-base metabolism, which may reduce risk of kidney stones and bone loss. Potassium-rich fruits and vegetables include leafy green vegetables, fruit from vines, and root vegetables. Meat, milk, and cereal products also contain potassium, but may not have the same effect on acid-base metabolism.
Copper
Copper is an essential trace mineral present in all body tissues. Cooper, along with iron, plays a role in the formation of red blood cells, and in maintenance of blood vessels, nerves, immune system, and bones.
Food sources of copper include, but are not limited to, oysters and other shellfish, whole grains, beans, nuts, potatoes, organ meats (kidneys, liver), dark leafy greens, dried fruits (such as prunes), cocoa, black pepper, and yeast. Normally, people have enough copper in the foods they eat; a lack of copper may lead to anemia and osteoporosis.
Table 20 shows the Food and Nutrition Board at the Institute of Medicine recommendations of dietary intake for copper. Specific recommendations depend on age, gender, and other factors (such as pregnancy). Women who are pregnant or lactating need higher amounts.
TABLE 20Recommended Dietary Allowances for Copper.Recommended Dietary Allowances for Copperμg/dayInfants0-6months2007-12months220Children1-3years3404-8years4409-13years700Adolescents and Adults14-18years89019 and older900Manganese
Manganese is an essential trace element. The classes of enzymes that have manganese cofactors are very broad and include such classes as oxidoreductases, transferases, hydrolases, lyases, isomerases, ligases, and reverse transcriptase. Manganese enables the body to utilize vitamin C, B1, biotin and choline. It plays a role at least in the production of fat, sex hormones, and breast milk in females.
Manganese is lost in milling and absorption is influenced negatively in the presence of large amount of calcium, phosphorous, zinc, cobalt and soy protein. Further, manganese is depleted in the soil by extensive use of chemical fertilizers, and food grown in such soil will have a low manganese content.
Dietary food sources of manganese include, but are not limited to, nuts, avocados, eggs, brown rice, whole grains, leafy greens and spices.
Fluoride
Fluoride occurs naturally in the body as calcium fluoride, which is mostly found in the bones and teeth. Small amounts of fluoride help prevent tooth decay. Fluoridation of tap water helps reduce cavities in children by 50% to 60%. Fluorides also help maintain bone structure. Low doses of fluoride salts may be used to treat conditions (such as menopause) that cause accelerated bone loss.
Food sources of fluoride include, but are not limited to, fluoridated water, and food prepared in fluoridated water. Natural sodium fluoride is present in the ocean, therefore most seafood contains fluoride. Fluoride deficiency may appear in the form of increased dental cavities, weak bones and teeth.
Table 21 shows the Food and Nutrition Board at the Institute of Medicine's recommendation for the dietary intake of fluoride. Specific recommendations depend on age and gender.
TABLE 21Recommended Dietary Intake for Fluoride.Recommended Dietary Intake for Fluoride (mg/day)Infants0-6months0.017-12months0.5Children1-3years0.74-8years1.09-13years2.0Adolescents and AdultsMales age 14-18years3.0Males over 18years4.0Females over 14years3.0Choline
Choline is a water-soluble essential nutrient that usually is grouped within the Vitamin B complex. Choline generally refers to the various quaternary ammonium salts containing the N,N,N-trimethylethanolammonium cation. These naturally occurring ammonium salts are found in the lipids that make up cell membranes and in the neurotransmitter acetylcholine. The FNB of the Institute of Medicine has established adequate intake (for adults) for this micronutrient of between 425 mg/day to 550 mg/day.
Foods richest in phosphatidylcholine (the major delivery form of choline) include, but are not limited to, egg yolks, soy, wheat germ, and cooked beef, chicken, veal and turkey livers. The most available choline dietary supplement is lecithin, derived from soy or egg yolks, which often is used as a food additive. Phosphatidylcholine also is available as a supplement, in pill or powder form. Supplementary choline also is available as choline chloride, which is available as a liquid due to its hydrophilic properties. Choline chloride is sometimes preferred as a supplement because phosphatidylcholine can have gastrointestinal side effects. The human body can make some choline, but generally it is recognized that it is important to get dietary choline as well. Although most foods have at least some choline, people may have to get enough in their diets, particularly if they do not eat many whole eggs.
Dietary Antioxidants
Oxidative stress has been attributed as a causative factor in a number of many chronic and degenerative diseases, such as heart disease, cancer, Sickle cell disease, Alzheimer's disease, Parkinson's disease, etc. Oxidative stress results from an imbalance between the production of reactive oxygen species (ROS) in the body and the body's ability to detoxify by ROS removal and repair of the resulting damage. Dietary antioxidants decrease the adverse effects of the reactive species. Diets rich in fruits and vegetables provide an excellent source of antioxidants. Oxygen Radical Absorption Capacity (ORAC) assay, for example, measures the degree of inhibition of peroxy-radical-induced oxidation by a given compound in a given chemical environment in Trolox equivalents (eg. μmol TE/100 g). Trolox equivalency can be used as a benchmark for measuring antioxidant capacity. Trolox or 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid is a water-soluble derivative of Vitamin E. Exemplary foods with high ORAC scores include but are not limited to berries, legumes, fruits and spices. There are conflicting reports on the recommended dietary allowance for ORAC. Some reports recommend 3,000-5,000 ORAC units, while others 12,000 ORAC units. The average daily intake in the U.S. has been estimated to be only 1,000-1,500 ORAC units.